The much-vaunted European Galileo navigation satellite constellation financed by the European Union (EU) and devised by the European Space Agency (ESA), is supposed to offer equivalent reliability and accuracy to the US GPS system. So there was more than a little embarrassment at the European Global Navigation Satellite Systems Agency (GSA) on 11 July when the entire system’s navigation signals appeared to fail. Media reports noted that the official Galileo status page suggested that all 22 operational satellites had been affected.
The outage was reportedly caused by a fault in the Precise Timing Facility (PTF) located at the Fucino ground station in Italy. This timing is key to the way the whole system works as the times generated by the satellites and their signal delays are all calibrated and referenced against it, which allows navigational receivers on Earth to calculate their positions. Many of these receivers, used in satnavs and mobile phones, have switched to GPS as their back-up navigation system.
The Galileo system also operates the Galileo Search and Rescue (SAR) service – a distress call relay system that is reported not to have been affected by the fault.
Update on 18 July 2019: The Galileo navsat system has been returned to service. https://www.gsc-europa.eu/system-status/Constellation-Information